As Bhanumati says, in restaurants which aren't purely vegetarian one has no assurance what kind of food one will get so such restaurants should be avoided by strict vegetarians.Since the restaurant admitted its fault of mixing orders some kind of private reconciliation should be made. The ridiculous American hobby of suing on every step benefits only lawyers.But it seems to me these folks want to make some money by suing the restaurant. They should remember that greed is itself an impurity of the mind. And it's a definitely bad PR for Vedic followers.

One can be purified in many ways. As far as Ganga-related purification goes, one can be sprinkled with Ganga water (usually available in temples, just like abhisheka water), chant some Ganga stotras (like Ganga stuti) or allegedly simply remember the name of Ganga. Expensive rituals are unnecessary.

"Duality is bondage before moksa and wisdom after realization. The duality accepted for the purpose of bhakti is sweeter than even non-duality." (from mangalacarana to Advaitasiddhi sara sangraha by Madhusudana Sarasvati, former advaitin)